Heat the oil or ghee in a heavy based pan or wok over high heat. Add the onion and stir fry for 3 minutes, or until starting to soften, but not brown.

Add the ginger, garlic and chillies and continue stir-frying for 30 seconds and then reduce heat to very low and leave to cook, stirring occasionally, until the onion is completely soft, but nothing browns.

Stir in the turmeric, cumin, coriander, chili and curry powders and continue cooking very gently for 5 minutes. Don't burn the spices or they will taste acrid; sprinkle on a few drops of water if you're worried. Remove the pan from the heat and allow to cool a little.

Put the water into a food processor or blender, then add contents of the pan. Blend until everything is very smooth, then add both flours and blend again. Put the puréed mixture back into the pan and simmer for 20-30 minutes (longer the better) over a very low heat, stirring occasionally. Add a little hot water if it starts to catch, but the idea is to gently fry the sauce so that it darkens in colour to an orangey brown. Once you have a thick paste, gradually stir in the stock and simmer until the sauce has reduced.

For the chicken

Season the cornflour and toss the chicken strips in this to coat them.

Heat the oil in a large fry pan over high heat.

Add the chicken and stir-fry for a couple of minutes, until they turn white.